Pressure balance of automotive air bypass valve

ABSTRACT

A solenoid device includes a solenoid assembly ( 30 ) including a stator ( 42, 32, 38 ) and a coil ( 36 ) for generating a magnetic field. An armature structure ( 14, 16 ) can move with respect to the solenoid assembly from a closed position, defining a working gap area ( 62 ) between the coil and a portion of the armature structure, to an open position in response to the magnetic field generated by the coil. Seal structure ( 22 ) is coupled with a proximal end of the armature structure and has a sealing edge ( 28 ) to seal with a component when the armature structure is in the closed position thereof. A spring ( 44 ) biases the armature structure to the closed position. Under certain operating conditions of the device, pressure is balanced between the working gap area and an area defined adjacent to 1) the sealing edge, and 2) a distal end of the armature structure.

This application is based on U.S. Provisional Application No. 61/066,349filed on Feb. 19, 2008, claims the benefit thereof for prioritypurposes, and is hereby incorporated by reference into thisspecification.

FIELD

The embodiment relates to a solenoid device for the bypass of intake airin an automotive application and, more particularly, to an air bypassvalve that has passive internal pressure balancing.

BACKGROUND

Automotive applications typically using an air pump, specifically aturbine, supercharger, or exhaust driven turbocharger, include gasoline,natural gas or diesel internal combustion engines. Other automotiveapplications also include fuel cells and fuel reformers, both requiringlarge volumes of air and often supplied by a turbine pump. While abypass valve may be utilized for any pump configuration, the exhaustdriven turbocharger is the typical application. The exhaust driventurbocharger is a free-spinning turbine with a shaft-separated splitimpeller, one end receiving force and a rotational moment from theexiting exhaust gases, the other end applying a pumping effect. As it isa free-spinning turbine, if the load on the air side suddenly increasesdue to a sudden decrease of demand by the engine, such as duringdeceleration, the pump will see a dramatic decrease in rotation and thecorresponding sudden decrease in cooling effect, lubricating effect, aswell as a high fatigue load on the impeller blades.

For the purpose of reducing the load on the turbocharger during suddendecreases of downstream flow, a bypass valve is typically applied toallow the impeller to continue moving air from the low pressure side tothe high pressure side at a rate now set by the impeller speed. It isdesirable to have a valve which can respond quickly when deceleration,load change or load shift point occurs, and recover quickly as whenacceleration or higher load is suddenly required. When not energized, itis desirable to minimize bypass leak and corresponding decrease in pumpefficiency when full throughput is required from pump. This must besatisfied with robustness as well as cost efficiency, while at the sametime not introducing undesirable noise, vibration and harshness, ornoise, vibration, harshness (NVH). Historically, bypass valves arecomparatively large, heavy electromagnets with machined parts andmultiple elastomeric diaphragms, bumpers and seals.

Thus, there is a need to provide an improved air bypass valve thatreduces noise and reduces the force to open and close the valve.

SUMMARY

An object of the present invention is to fulfill the need referred toabove. In accordance with the principles of an embodiment, thisobjective is obtained by providing a pressure-balanced solenoid deviceincluding a solenoid assembly having a stator and a coil constructed andarranged to be energized to generate a magnetic field. An armature andseal assembly includes an armature structure constructed and arranged tomove with respect to the solenoid assembly from a closed position,defining a working gap area between the coil and a portion of thearmature structure, to an open position in response to the magneticfield generated by the coil. The armature structure includes a proximalend and a distal end. The armature and seal structure also includes aseal structure coupled with proximal end of the armature structure. Theseal structure has a sealing edge constructed and arranged to seal witha component when the armature structure is in the closed positionthereof. A spring biases the armature structure to the closed position.The armature and seal assembly includes pressure balancing structureconstructed and arranged to provide a pressure balance between theworking gap area and an area defined adjacent to 1) the sealing edge,and 2) the distal end of the armature structure. The solenoid device maybe an air bypass valve for an automobile.

In accordance with another aspect of the embodiment, a method ofbalancing pressure in a solenoid device provides a solenoid assemblyincluding a stator and a coil constructed and arranged to be energizedto generate a magnetic field. An armature structure is provided and isconstructed and arranged to move with respect to the solenoid assemblyfrom a closed position, defining a working gap area between the coil anda portion of the armature structure, to an open position in response tothe magnetic field generated by the coil. The armature structureincludes a proximal end and a distal end. A seal structure is coupledwith proximal end of the armature structure. The seal structure has asealing edge constructed and arranged to seal with a component when thearmature structure is in the closed position thereof. The armaturestructure is biased to the closed position. The method ensures thatunder certain operating conditions of the device, pressure is balancedbetween the working gap area and an area defined adjacent to 1) thesealing edge, and 2) the distal end of the armature structure.

Other objects, features and characteristics of the present invention, aswell as the methods of operation and the functions of the relatedelements of the structure, the combination of parts and economics ofmanufacture will become more apparent upon consideration of thefollowing detailed description and appended claims with reference to theaccompanying drawings, all of which form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from the following detaileddescription of the preferred embodiments thereof, taken in conjunctionwith the accompanying drawings, wherein like reference numerals refer tolike parts, in which:

FIG. 1 is a view of a solenoid device in the form of an automotive airbypass valve in accordance with an embodiment of the present invention.

FIG. 2 is an exploded view of an armature and seal assembly of the airbypass valve of FIG. 1.

FIG. 3 is an assembled view of the armature and seal assembly of FIG. 2.

FIG. 4 is an exploded view of a solenoid assembly of the air bypassvalve of FIG. 1.

FIG. 5 is an assembled view of the solenoid assembly of FIG. 4.

FIG. 6 is an exploded view of the armature assembly being inserted intothe overmolded solenoid assembly of the air bypass valve of FIG. 1.

FIG. 7 is a sectional view of a solenoid device of FIG. 1 shown with anarmature in a closed position.

FIG. 8 is a view of the solenoid device of FIG. 7, with the armatureshown in an open position.

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT

Referring to FIG. 1, a solenoid device in the form of an air bypassvalve for a vehicle is shown, generally indicated at 10, in accordancewith an embodiment of the invention. The air bypass valve detailedherein comprises about fourteen basic parts, potentially none of whichare machined, but all of which are preferably injection molded, stamped,or drawn from sheet stock. Such a configuration provides a realizedsavings in used material volume and type, along with the correspondingenvironmental and economic benefits.

With reference to FIGS. 2, 3, and 7, an armature and seal assembly isshown, generally indicated at 12. The armature and seal assembly 12 isthe moving component of the valve 10 and includes an armature structurehaving an armature 14 and a composite, resin or polymer molded pivotgland structure 16 either molded onto a proximal end 15 of the armature14 or assembled thereto with a mechanical retainer (not shown). Thus,the gland structure 16 can be considered to be part of the armature 14and includes a gland member 18, the function of which will be explainedbelow. A dynamic seal 20 of an appropriate material is eitherincorporated as part of the gland structure 16, co-injection moldedtherewith, or coupled thereto as a separate component. The dynamic seal20 reduces air leakage past the armature 14, reducing both air noise andbypass leakage. Finally, a hard seal structure 22, preferably made ofsimilar materials as the gland structure 16, has a pivot member 23 thatis preferably snapped together with the gland member 18. As best shownin FIG. 7, the mating co-centric spherical surfaces (external surface 24of gland member 18 and internal surface 26 of the pivot member 23) forma pivot function such that the seal structure 22 can pivot with respectto the gland structure 16 and thus the armature 14. The 360° pivotfunction is accommodates any dimensional variance from ideal between theaxis of the solenoid assembly 30, mounting face of the complete assemblyand the sealing surface and mounting surfaces of the respective airmanifold or component to which the valve assembly 10 is attached. Byaccommodating these variances, bypass leak is minimized and durablefunction of the solenoid maximized in allowing the hard sealing edge 28of the hard seal structure 22 to mate with the opposite mounting sealingsurface as parallel as possible. It is noted that the inner sphericalsurface can be part of the gland member with the outer spherical surfacebeing part of the pivot member 23.

With reference to FIGS. 4, 5, and 8, solenoid assembly, generallyindicated at 30, is shown. The solenoid assembly 30 includes thestationary magnetic components of the valve 10 and includes a magnetic(e.g., ferrous) housing 32 that provides a flux return path and a datumenclosure for other parts of the valve 10. A coil bobbin 34 is woundwith an electromagnet coil 36 of a suitable wire material of anappropriate number of turns to provide the resistance and ampere-turnsnecessary for proper function with the available control electronics.The coil 36 is not shown in FIG. 4. The coil bobbin 34 with coil 36 isinserted into the housing 32, and a magnetic (e.g., ferrous) flux ring38 is pressed into the housing 32, retaining the coil bobbin 34 andproviding a specific working magnetic pole-type to the armature 14. Aspring pin 40 is provided in the housing 32 and a magnetic (e.g.,ferrous) end cap 42 is pressed onto the housing 32, thereby retainingthe spring pin 40. As shown in FIG. 7, upon assembly, the spring pin 40is received in a bore 41 in a stem portion 55 of the armature 14 so thata first end 43 of the spring pin 40 engages the spring 44 and a secondend 45 of the spring pin 40 is adjacent to the end cap 42. The springpin 40 provides an axial flux path into the armature 14 as well asguides a closing return spring 44, also in bore 41, in the finalassembly. The stator of the solenoid assembly 30 comprises the lumpmagnetic circuit formed by the magnetic flux ring 38, the magnetichousing 32, the magnetic end cap 42 and, if desired, the spring pin 40.

With reference to FIG. 6, the solenoid assembly 30 is over-molded withan appropriate polymer or resin to provide the final encapsulation andretention main housing 46 of all stationary parts for the air bypassvalve 10. FIG. 6 shows the final assembly of the valve 10 and also showshow the encapsulation provides a customer specified flange 48 formounting by the end user. Preferably the flange 48 includes mountingholes 50 that receive, preferably in an encapsulated manner, a supportboss 52 therein. In addition, the main housing 46 includes impactprotection structure that protect the armature and seal assembly 12 fromdrops and handling, as well as any manifold sealing O-rings. In theembodiment, the impact protection structure includes a plurality of tabs54 extending in an annular manner from a bottom surface 56 of thehousing 46 so as to generally surround the seal structure 22 of thearmature and seal assembly 12.

In the final assembly steps, the closing return spring 44 is insertedinto the armature 14, and the armature and seal assembly 12 is theinserted into the solenoid assembly 30. More particularly, a stemportion 55 of the armature 14 is received in a bore 57 in the coilbobbin 34. An O-ring 58 provides a seal with respect to an air manifold(not shown) to which the valve 10 is attached.

Basic operation of the valve 10 will be appreciated with reference toFIGS. 7 and 8. FIG. 7 shows the closed position the valve 10 andarmature 14 (biased by spring 44) when the electromagnetic coil 36 isnot energized via leads 60. In this position, the magnetic gap workingvolume area 62 is clearly shown between the coil 36 and a generallycylindrical base 63 of the armature 14. The sealing edge 28 is anextended position so as to engage with the manifold surface (not shown).FIG. 8 shows the open position of the valve 10 and armature 14 whenvoltage is applied to the coil 36 such that a force on the armature 14overcomes the force of spring 44. In this position, the sealing edge 28is a retracted position so as to disengage with the manifold surface(not shown).

As best shown in FIG. 7, advantageous passive internal pressure balanceis realized through air passing into a pressure balancing structure thatincludes a first, axially extending port 64 and a second port 66extending transversely with respect to the first port 64 and incommunication therewith. The first port 64 extends axially through theseal structure 22, the gland member 18 and into the armature 14 and canbe considered to be part of bore 41 in the armature 14. The port 66 hasa reduced diameter portion 65 in the armature 14. The second port 66extends transversely through the reduced diameter portion 65 to theouter periphery of the stem portion 55 of the armature 14. The secondport 66 allows pressure balance between the magnetic working gap area 62and an area 68 adjacent to the diameter defining the sealing edge 28.The first port 65 continues upward to the bore 41 that houses the spring44, balancing the pressure there. The bore 41 can be considered to bepart of the first port 64.

Finally, the pressure balancing structure includes flats 70 in theperiphery of the rod-shaped stem portion 55 of the armature 14 thatcreate a passage communicating an area 72 adjacent to the distal end 74of the armature 14 and proximal to the spring pin 40, with the magneticworking gap area 62. Thus, a pressure balance is permitted between thearea 72 and the working gap area 62. The ports 64, 66 and flats 70 onthe armature 14 are conveniently incorporated in a metal injectionmolded (MIM) part, as the flats are already added for knit line reliefin the mold design. Passage sizes are roughly selected to providepneumatic damping and smoothing of the opening and closing strokes.

Thus, the valve 10 is an electronically activated electromagnetic valvewhose purpose is to bypass working air from the high pressure side tothe low pressure side of a manifold pressure boost pump, turbocharger,supercharger, turbine air pump or similar. The air bypass valve 10utilizes a novel passive internal pressure balancing method, reducingthe noise of operation and reducing the force required to both open andclose the valve. The air bypass valve provides the functionality for thesuccess, long term operation and efficiency of air boost systems, whichdepend on responsiveness to dynamic changes and robustness of operation.

The foregoing preferred embodiments have been shown and described forthe purposes of illustrating the structural and functional principles ofthe present invention, as well as illustrating the methods of employingthe preferred embodiments and are subject to change without departingfrom such principles. Therefore, this invention includes allmodifications encompassed within the spirit of the following claims.

1. A solenoid device comprising: a solenoid assembly comprising: astator, and a coil constructed and arranged to be energized to generatea magnetic field, an armature and seal assembly comprising: an armaturestructure constructed and arranged to move with respect to the solenoidassembly from a closed position, defining a working gap area between thecoil and a portion of the armature structure, to an open position inresponse to the magnetic field generated by the coil, the armaturestructure including a proximal end and a distal end, and a sealstructure coupled with proximal end of the armature structure, the sealstructure having a sealing edge constructed and arranged to seal with acomponent when the armature structure is in the closed position thereof,and a spring biasing the armature structure to the closed position,wherein the armature and seal assembly includes pressure balancingstructure constructed and arranged to provide a pressure balance betweenthe working gap area and an area defined adjacent to 1) the sealingedge, and 2) the distal end of the armature structure, wherein thepressure balancing structure comprises: a first port extending axiallythrough the seal structure and the armature structure, a second port incommunication with and extending transversely from the first port, thesecond port extending to a periphery of the stem portion such that undercertain conditions, the second port can communicate with the working gaparea and a passage, external of the armature, communicating the workinggap area with the area defined adjacent to the distal end of thearmature.
 2. The device of claim 1, wherein the armature structureincludes an armature having a base and a generally rod-shaped stemportion extending from the base, and wherein the coil is disposed abouta bobbin that is received in an interior portion of a magnetic housingof the stator, the bobbin having a bore there-through, the stem portionof the armature being received in the bore.
 3. The device of claim 2,wherein the passage is defined by flats in the periphery of the stemportion of the armature.
 4. The device of claim 3, wherein the spring isdisposed in the first port.
 5. The device of claim 4, further comprisinga spring pin having a first end engaging an end of the spring, and amagnetic end cap adjacent to a second end of the spring pin such thatthe spring pin provides an axial flux path into the armature and guidesthe spring.
 6. The device of claim 1, wherein the device is an airbypass valve for a vehicle, wherein the seal structure is coupled witharmature structure so that the seal structure can pivot with respect tothe armature structure, the seal structure having a sealing edgeconstructed and arranged to seal with a component when the armaturestructure is in the closed position thereof.
 7. The device of claim 6,wherein the armature structure includes an armature and a glandstructure coupled thereto, the gland structure having a gland memberdefining a generally spherical surface, and the seal structure has apivot member defining a generally spherical surface that is engaged withthe generally spherical surface of the gland member permitting pivotingof the seal structure with respect to the armature.
 8. The device ofclaim 7, further comprising a dynamic seal associated with the glandstructure, the dynamic seal being constructed and arranged to reduce airleakage past the armature.
 9. The device of claim 2, further comprisinga main housing defining a plastic overmold covering the magnetichousing.
 10. The device of claim 9, wherein the main housing includesimpact protection structure constructed and arranged to protect sealstructure.
 11. The device of claim 10, wherein the impact protectionstructure includes a plurality of tabs extending in an annular mannerfrom an end of the main housing so as to generally surround the sealstructure.
 12. A method of balancing pressure in a solenoid device, themethod comprising: providing a solenoid assembly including a stator anda coil constructed and arranged to be energized to generate a magneticfield, providing an armature structure constructed and arranged to movewith respect to the solenoid assembly from a closed position, defining aworking gap area between the coil and a portion of the armaturestructure, to an open position in response to the magnetic fieldgenerated by the coil, the armature structure including a proximal endand a distal end, providing a seal structure coupled with proximal endof the armature structure, the seal structure having a sealing edgeconstructed and arranged to seal with a component when the armaturestructure is in the closed position thereof, biasing the armaturestructure to the closed position, and ensuring that under certainoperating conditions of the device, pressure is balanced between theworking gap area and an area defined adjacent to 1) the sealing edge,and 2) the distal end of the armature structure, wherein the step ofensuring that pressure is balanced includes providing pressure balancingstructure comprises: a first port extending axially through the sealstructure and the armature structure, a second port in communicationwith and extending transversely from the first port, the second portextending to a periphery of the stem portion such that under certainconditions, the second port can communicate with the with the workinggap area, and a passage, external of the armature, communicating theworking gap area with the area defined adjacent to the distal end of thearmature.
 13. The method of claim 12, wherein the step of providing thearmature structure includes providing an armature having a base and agenerally rod-shaped stem portion extending from the base, and whereinthe coil is disposed about a bobbin that is received in an interiorportion of a magnetic housing of the stator, the bobbin having a borethere-through, the stem portion of the armature being received in thebore.
 14. The method of claim 13, wherein the passage is defined byflats in the periphery of the stem portion of the armature.
 15. Themethod of claim 14, wherein the step of biasing the armature structureincludes providing a spring in the first port.
 16. The method of claim12, wherein the device is an air bypass valve for a vehicle and thecomponent is a manifold.